Surface modified PVDF nanofiber supported thin film composite membranes for forward osmosis

Abstract

Hydrophilic electrospun nanofiber supported thin film composite (TFC) membranes have recently been considered for forward osmosis (FO). Our previous work has shown that the high degree of swelling in hydrophilic nanofibers compromises fiber strength and membrane integrity. To reduce swelling, we propose to modify a non-swelling hydrophobic fiber to make it hydrophilic and fully wettable without negatively impacting the mechanical properties of the material. The method chosen for this work involves the interfacial polymerization of 1,6-hexane diamine and adipoyl chloride to form nylon 6,6 directly onto electrospun PVDF fibers. The result is a dual benefit of hydrophilization and strengthening of nanofibers to improve their wettability. The modified nanofibers exhibited significantly lower swelling propensity than intrinsically hydrophilic nylon 6,6 nanofibers due to the hydrophobic core fiber, and are thus able to retain strength in an aqueous environment. These modified PVDF supports were used in making TFC membranes that exhibited excellent flux performance and one of the lowest structural parameters reported in open literature.